/**
 * Created with IntelliJ IDEA.
 * Description:
 * User: LENOVO
 * Date: 2024-08-09
 * Time: 23:55
 */
class BinaryTree {

    static class TreeNode {
        public char val;
        public TreeNode left;//左孩子的引用
        public TreeNode right;//右孩子的引用

        public TreeNode(char val) {
            this.val = val;
        }
    }


    /**
     * 创建一棵二叉树 返回这棵树的根节点
     *
     * @return
     */
    public TreeNode createTree() {
        TreeNode A = new TreeNode('A');
        TreeNode B = new TreeNode('B');
        TreeNode C = new TreeNode('C');
        TreeNode D = new TreeNode('D');
        TreeNode E = new TreeNode('E');
        TreeNode F = new TreeNode('F');
        A.left = B;
        A.right =C;
        B.left = D;
        B.right = E;
        C.left = F;
        return A;
    }

    // 前序遍历
    public void preOrder(TreeNode root) {
        if(root == null){
            return;
        }
        System.out.println(root.val);
        preOrder(root.left);
        preOrder(root.right);
    }

    // 中序遍历
    void inOrder(TreeNode root) {
        if(root == null){
            return;
        }
        preOrder(root.left);
        System.out.println(root.val);
        preOrder(root.right);
    }

    // 后序遍历
    void postOrder(TreeNode root) {
        if(root == null){
            return;
        }
        preOrder(root.left);
        System.out.println(root.val);
        preOrder(root.right);
    }

    public static int nodeSize = 0;

    /**
     * 获取树中节点的个数：遍历思路
     */
    void size(TreeNode root) {
        if(root == null){
            return;
        }
        nodeSize++;
        size(root.left);
        size(root.right);
    }

    /**
     * 获取节点的个数：子问题的思路
     *
     * @param root
     * @return
     */
    int size2(TreeNode root) {
        if(root == null){
            return 0;
        }
        return size2(root.left) + size2(root.right) + 1;
    }


    /*
     获取叶子节点的个数：遍历思路
     */
    public static int leafSize = 0;

    void getLeafNodeCount1(TreeNode root) {
    }

    /*
     获取叶子节点的个数：子问题
     */
    int getLeafNodeCount2(TreeNode root) {
        if(root == null){
            return 0;
        }
        if(root.left == null && root.right == null){
            return 1;
        }
        return getHeight(root.left) + getHeight(root.right);
    }

    /*
    获取第K层节点的个数
     */
    int getKLevelNodeCount(TreeNode root, int k) {
        //就是左节点的k-1层节点数加右节点的k-1层节点数，该末尾条件为k-1 == 1
        if(root == null){
            return 0;
        }
        if( k - 1 == 1){
            return 1;
        }
        return getKLevelNodeCount(root.left,k-1) + getKLevelNodeCount(root.right,k - 1);
    }

    /*
     获取二叉树的高度
     时间复杂度：O(N)
     */
    int getHeight(TreeNode root) {
        if(root == null){
            return 0;
        }
        int a = getHeight(root.left);
        int b = getHeight(root.right);
        return Math.max(a , b) + 1;

    }


    // 检测值为value的元素是否存在
    public TreeNode find(TreeNode root, char val) {
        if(root == null){
            return null;
        }
        if(root.val == val){
            return root;
        }
        TreeNode leftF = find(root.left,val);
        if(leftF != null){
            return leftF;
        }
        TreeNode leftR = find(root.right,val);
        if(leftR != null){
            return leftF;
        }
        return null;
    }

    //层序遍历
    void levelOrder(TreeNode root) {

    }


    // 判断一棵树是不是完全二叉树
    boolean isCompleteTree(TreeNode root) {
        return true;
    }
}
public class Homework {
    public static void main(String[] args) {
        BinaryTree binaryTree = new BinaryTree();
        BinaryTree.TreeNode root = binaryTree.createTree();
        binaryTree.preOrder(root);
        binaryTree.size(root);
        System.out.println(BinaryTree.nodeSize);
        System.out.println(binaryTree.getHeight(root));
        System.out.println(binaryTree.find(root,'B').val);
    }
}
